Weed Management Handbook

clethodim (Select or Arrow)

Rate 0.9 to 0.125 lb ai/A

Time Apply to sandbur 2 to 6 inches tall.

Remarks See label for crops and sites where clethodim may be used. If required, apply with suitable surfactant. Acts very slowly, taking at least 2 weeks and often 4 weeks to show effects. Do not apply to stressed grasses.

2,4-D

Rate 2 lb ae/A in 50 gal of water

Time Apply before any blossoms open, preferably on new seedlings after germination.

Remarks Repeat applications as needed. Klamath beetles are preferred to control large infestations.

Caution Avoid drift to sensitive crops.

picloram (Tordon)

Rate 0.25 to 0.5 lb ae/A

Time When plants are fully emerged up to flower bud formation.

Remarks Plants should be actively growing at the time of application. To be used on rangeland or permanent grass pastures.

2,4-D LV ester

Rate 2 lb ae/A

Time Timing is critical for effective control. Apply during active sagebrush growth in spring when Sandberg bluegrass flowers, phloxes are forming seed, and larkspur is flowering near stem top.

See Biological Control section in this handbook.

2,4-D LV ester

Rate Use a mixture of 1.5 lb ae 2,4-D, 50 gal water, and 2 gal diesel or a nonionic surfactant for spot treatments.

Time Apply in April or May after rush has made good spring growth.

Remarks Foliage must be thoroughly wet.

Caution Avoid drift to sensitive crops.

glyphosate

Remarks Reported to control this plant, although data are lacking in the Pacific Northwest. Follow label instructions.

Site of action Group 9: inhibits EPSP synthase

Chemical family None generally accepted

imazapyr (Arsenal)

2,4-D or picloram (Tordon) or dicamba (Clarity) or 2,4-D + dicamba (Weedmaster) or triclopyr + 2,4-D (Crossbow)

Rate 1 to 2 lb ae/A 2,4-D LV ester or 2,4-D amine; or 0.25 lb ae/A picloram; or 1 lb ae/A dicamba; or 2 quarts/A Weedmaster; or 1.5 to 2 quarts/A Crossbow

2,4-D ester

Rate 2 lb ae/A

Time Apply after all plants have emerged but before flowering.

Remarks Foliage must be thoroughly wet. Use 50 gal/A of water.

Caution Avoid drift to sensitive crops.

Site of action Group 4: synthetic auxin

2,4-D LV ester

Rate 3 lb ae/A

Time Apply when rabbitbrush has 3 inches of new spring growth.

Remarks Soil moisture should be above wilting coefficient. If Sandberg bluegrass has dried up or lost its color, soil is too dry for rabbitbrush active growth, and it is too late to spray.